A steel structure having main structural members like columns, beams and so on, which are made of steel, is adequate for high-rise and long-span structures and has excellent earthquake resistance and constructability because of the high strength steel used therefor, so that the steel structure has been widely used.
The columns or beams constituting the steel structure are generally manufactured in advance in a factory according to their designed sizes under their designed stress, and next, the steel beams are coupled to the columns in construction site.
In conventional practice, as shown in FIG. 1, a bracket 4 is integrated with a steel column 1 and then connected to a steel beam 3 so as to connect the steel beam 3 to the steel column 1. When the bracket 4 is connected to the steel beam 3, as shown, eight slice plates PL are mounted on the top and underside surfaces of the upper and lower flanges of the bracket 4 and the steel beam 3 and both surfaces of the webs of the bracket 4 and the steel beam 3 and then fastened thereto by means of bolts B.
Accordingly, bolt coupling holes should be punched on the steel beam 3, and in this case, the machining cost for the steel beam 3 is very expensive. In more detail, the punching work itself is simple, but handling costs for lifting and fixing the heavy steel beam 3 are much needed. In this case, the number of bolt coupling holes of the bracket 4 is the same as of the steel beam 3, but the machining cost for the heavy steel beam 3 is higher than that for the bracket 4.
The number of bolts B needed on the bracket 4 is the same as needed on the steel beam 3, so that the number of bolts needed for moment transmission becomes double.
Accordingly, the conventional joint structure of steel beam as shown in FIG. 1 undesirably requires many bolts B, which is very disadvantageous in view of the period of construction and the construction cost thereof.
Further, since the slice plates PL are fixed to the top and underside surfaces of the upper and lower flanges of the bracket 4 and the steel beam 3 and both surfaces of the webs of the bracket 4 and the steel beam 3, at least a party of two workers is needed to connect the bracket 4 to the steel beam 3, and in the step of temporarily fastening the slice plates PL to the bracket 4 or the steel beam 3 in high altitude, safety accidents caused by falls of the slice plates PL or bolts B may happen.
Furthermore, the conventional joint structure of steel beam as shown in FIG. 1 is applied only when the H beam 3 is coupled to the H steel bracket 4, so that it is impossible to conduct the connection of a composite steel beam like a TSC (T-type Steel Concrete) beam.
When a deck plate is installed, in addition, the portions where the slice plates PL are located protrude from the top of the upper flange of the steel beam 3, so that separate plates are welded to the sides of the upper flanges of the bracket 4 and the steel beam 3 on the slice plates PL and the deck plate is then installed on the welded plates, thereby undesirably needing the separate plate welding work.
So as to solve the above-mentioned problems, as shown in FIG. 2, a steel beam 3 is connected directly to the side surface of a steel column 1 by means of tension bolts as fastening means.
Because of a construction error, in this case, the steam beam 3 has a shorter length than clear spacing of the steel column 1, so that shim plates SP are fittedly inserted into gaps occurring between the steel beam 3 and the steel column 1 in construction site.
However, the gaps between the steel beam 3 and the steel column 1 are varied in size according to their construction environment. Accordingly, the shim plates SP having various thicknesses are first prepared, and they should be selected and fitted to the gaps one by one. Moreover, it is impossible to insert the shim plates SP on a weak axis of the steel column 1.
Furthermore, there is proposed a conventional method wherein the end portions of a bracket and a steel beam are slanted correspondingly to each other to remove a construction error (which is disclosed in Korean Patent Application Laid-open No. 10-2006-0071525).
According to the conventional technique, however, bent plates for connecting a web and a beam are complicatedly manufactured and connected.
Further, bolts of the web just connect and fix adjacent members, but they cannot transfer a moment. Accordingly, welding work for adjacent upper and lower flanges is needed in construction site, which causes degradation in the quality of the connection structure and safety accidents.